1. Field of the Invention
The invention relates to a silicone composition that can be crosslinked to give elastomers and that comprises polyglycol ethers which can be incorporated by crosslinking and which have at least one unsaturated group.
2. Description of the Related Art
In insulation materials such as silicone elastomers, electrical charges can arise through friction or in direct-voltage applications, and because of very high volume resistivities in the region of about 1015 Ω cm these can only be dissipated very slowly.
Any lowering of volume resistivity achieved with electrically conductive fillers such as carbon black, graphite, or metal powder has only low reproducibility and is therefore very unreliable. These additives moreover have an adverse effect on breakdown voltage.
U.S. Pat. No. 6,251,990 B1 describes addition-crosslinkable silicone rubber compositions for high-voltage insulators which comprise, as agents providing thixotropic properties, from 0.1 to 50 parts by weight of siloxane-polyether block copolymers per 100 parts by weight of siloxane comprising alkenyl groups. These compositions comprise large amounts of aluminum hydroxide (ATH) in order to improve electrical insulator properties. However, large amounts of aluminum hydroxide impair the mechanical properties of the silicone rubber.
DE 10020670 describes polyorganosiloxanes which have been modified with polyalkylene glycol moieties and which, because of the high content of more than 50% by weight of polyalkylene glycol moieties, are highly hydrophilic. These polyorganosiloxanes serve as additives in paints and other coating materials, and in polyurethane foams.
EP 1922352 describes the production of hydrophilic silicone organocopolymers by means of free-radical polymerization. The silicone organocopolymers comprise polyglycol ether moieties.
EP 602128 describes a polysiloxane composition which gives permanently water-wettable vulcanizates and for which a siloxane comprising polyglycol ether moieties and vinyl moieties is incorporated as modifier by crosslinking into the polysiloxane composition to provide hydrophilic properties. The polysiloxane composition is used as dental impression composition.